Twins/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A boy, Tim, writes on paper at a desk. A robot, Moby, walks over to him. TIM: Oh, hey Moby. Another Moby stands next to Moby. MOBY 2: Beep. TIM: Oh hey, Moby? Tim reads from a typed letter. TIM: Dear Tim and Moby, there are two sets of twins in my class at school. One set is a pair of boys who look exactly the same, and the other set is two girls who look only sort of alike. What's up with that? From Gerald. TIM: That's pretty unusual to have two sets of twins in your class. A split image shows two boys who look exactly the same on one side, and two girls who do not look the same, on the other side. The two girls are the same height and are dressed similarly. TIM: I think it's safe to bet that the boys are identical twins, and the girls are fraternal twins. MOBY: Beep. TIM: Well I, MOBY 2: Beep. TIM: Hang on, I'm getting to that. An image shows a human fetus. An animation shows a sperm cell fertilizing an egg cell. The cell divides. TIM: Having a twin is something that's determined even before birth. A woman gets pregnant when one of her egg cells is fertilized by a male sperm cell. That means that the egg cell and sperm cell have joined together to make a whole new kind of cell inside of a woman. That cell divides and develops into a fetus. The fetus grows for nine months until it's ready to be born. An animation shows two egg cells being fertilized, each by a different sperm cell. An image shows twin fetuses. TIM: Sometimes two egg cells are released at the same time and each egg is fertilized by a different sperm. The eggs travel to the mother's uterus and grow alongside each other for the same period of time. At the end of nine months, two babies are born. Since these babies are the result of two different eggs, and two different sperm, they have different genetic makeup. That means that they may look like brothers or sisters, but they won't look the same because they have different sets of genes. MOBY: Beep. TIM: Right, fraternal twins are really only as similar as any two siblings. A set of fraternal twins can be two girls, two boys, or a boy and a girl. MOBY: Beep. TIM: Right, or a girl and a boy. An animation shows a sperm fertilizing an egg cell. The egg cell splits into two cells. An image shows twin fetuses. TIM: Identical twins are a different story: they come from the same egg and sperm combo. Once in a while, a fertilized egg will split into two cells that both develop into fetuses. When there is only one egg to begin with, the fetuses end up with exactly the same genes. They are the products of the same sperm and the same egg that happen to split into two pieces. An image shows a set of identical twin girls and boys. TIM: This mean that they will definitely be the same sex, two girls and two boys, and it's darn near impossible to tell them apart. MOBY: Beep. TIM: Well, that's true. There is a third, very rare, type of twins. An image shows twin fetuses joined in the back. TIM: Conjoined twins are connected at some part of their body. This can happen when a developing embryo starts to separate into identical twins, but then stops before the separation is complete. In most cases, doctors try to separate them surgically. MOBY and MOBY 2: Beep. TIM: OK, this is fun and all, but which of you is the real Moby? Moby points to Moby 2. TIM: You made him out of spare parts? Moby 2 points to Moby. TIM: You made him out of spare parts? This isn't gonna end well.Category:BrainPOP Health Transcripts Category:BrainPOP Transcripts